A change requested by the Trump administration will allow the NSA to keep information it acquired illegally.
This spring, the government announced a change to the way the National Security Agency collects information targeting foreigners, using the telecom backbone in what it calls "upstream" collection. Whereas for 10 years, the agency had sucked up communications mentioning a target's selector—say, collecting all emails sent to someone in this country that include Osama bin Laden's phone number in the body of the email—in April it stopped doing so domestically (though it will still do tons of it in collection overseas).
Not long after the announcement, the government released documents explaining why it had dropped this kind of collection, which it calls "about" collection. Those documents amounted to a confession that the NSA failed to follow rules the Foreign Intelligence Surveillance Court put in place in 2011 to ensure upstream collection complied with the Fourth Amendment.
There was a stink, at the time, accusing the Obama Administration of using Section 702 of FISA—which only permits the government to target foreigners—of using it to spy on Americans for five years. Those accusations were, technically, true (the NSA attributed such spying to technical failures, not legal ones). But the truth is far more troubling. In fact, from 2004 to 2016, the NSA was always engaging in collection the FISC would go on to deem unauthorized. For 12 years, under both the Bush and Obama Administrations, the NSA was collecting information that, if retained, would break the law.
But under the current presiding judge, overseeing the plans of the Trump Administration, NSA will be allowed to keep such data, a change from her three predecessors.
https://motherboard.vice.com/en_us/article/vb7eg9/the-nsas-12-year-struggle-to-follow-the-law